The use of threaded mechanical fasteners are widespread and provide an indispensable means of assembly in nearly all products and components whether for industrial or consumer usage. While threaded fasteners allow reliable and consistent connection between mating components in static conditions, dynamic loading, stress reversals, thermal expansion, and vibration cause conventional threaded fasteners to loosen.
Manufacturing tolerances and thread allowances inherently provide thread clearance between the external thread of a screw or bolt and the internal threads of a tapped hole or nut. These clearances combined with the aforementioned dynamic loadings reduce the threaded fastener's frictional resistance to rotation. When this frictional resistance is reduced, even for a micro second, the same tensile force in the bolt or screw that was developed from the initial installation torque allows the mating threads to slide down the ramp of the helix angle a minute amount. Over a number of cycles, the motion continues until the bolt pre-load is completely lost resulting in joint separation. Threaded fasteners can then fail or fall completely out. Depending on the application, this failure can be catastrophic.
During dynamic cycling, service loads impact the threads causing the crest of the threads to shear. In time, the threads, internal and external can be damaged to the point where they cannot be reused or the assembly cannot be conveniently disassembled. This can result in significant expense in the form of repair or component replacement.
Gasketed joints in high vibration environments must have sufficient bolt pre-load to resist loosening. This pre-load can exceed the strength of the gasket material resulting in an unsealed joint.
The need arises for a fastening system to overcome the aforementioned problems.